Until the occurrence of World War II, generally in the period 1940 to 1945 there had been plentifully available to fishermen, both commercial fishermen and sports fishermen, a type of lure the body of which was carved from natural materials such as bone, ivory and horn. The principal source of these lures was the Orient, particularly Japan. The lures were used mainly for trolling and they were well adapted to this type of underwater activity because the specified natural substances have specific gravities falling in the range between values 1.4 and 2.1.
Typically, these carved lures had a flat surface and a rounded surface, providing cross-sectional contours resembling a bow or, more exactly, an arc subtended by a chord, with maximum width and thickness located about one third of the distance from the leading end of the lure. From that point forward they tapered in width and in thickness along curves to an approximation of a point at the tip. In the opposite direction they tapered in width and in thickness along gentler curves to a somewhat blunt trailing end. One or more barbed hooks were attached to their undersurfaces to extend beyond their blunt trailing ends, and at their leading ends they were provided with means such as rings for connection of the lures to lines. They were characterized by a high degree of success in attracting fish.
Since the close of that war, lures of this type have virtually disappeared from the market. Among reasons suggested for the disappearance of these lures from the market are that the carving of such lures has become a lost art, and/or adverse economics of the product. The net result is that a useful tool is no longer available to the fisherman.
Efforts to fabricate, in other ways than by carving, lures having attributes matching those of the carved bone, ivory and horn lures have heretofore been unsuccessful. One of these efforts resulted in the production of lures molded from plastics and consisting solely of the plastics. These lures had specific gravities in the immediate vicinity of unity and therefore were considerably lighter, in terms of unit of weight per unit of volume than the carved lures and therefore did not readily submerge nor remain submerged nor execute movements when drawn through water comparable with those of the lures made from the aforementioned natural substances. In order to increase the specific gravity of the plastic lures, weighting components were added such as, for example, plates of metal attached to the flat underside of the lure or pieces of metal embedded in the plastic lure. These added metal objects achieved specific gravities of the weighted lures comparable with those of the lures carved from natural products but their motions in the water were not comparable with those of the carved lures and they have been unsuccessful as devices for catching fish.
Still another approach to a substitute for the carved bone or ivory lures was the casting of lure bodies from metal alloys. It was found to be impossible to achieve specific gravities as low as the range of values for the bone, horn and ivory lures, and because of the higher specific gravities the metal alloy lures behaved differently in the water than did the carved lures and failed to attract fish to any extent comparable with that of the carved lures.